The latest version (1.0.13) of our Firefox add-on has finally been approved by Mozilla, so it’s now online at Grammar and Spell Checker - LanguageTool – Get this Extension for 🦊 Firefox (en-US)
If you have the add-on installed already, you’ll soon get the update automatically. This update fixes storing the preferences, so you can now visit the add-on settings dialog again and it will actually store your changes.